1. Field of the Invention
The present invention relates to a production management system used in fabricating semiconductor devices and, more particularly, to-a chip management system which controls the production of each individual chip mounted on a wafer and needs differing types of processing information, a method of processing inputs thereto, and a lot processing system therefor.
2. Description of the Related Art
In conventional production management systems for controlling the production of semiconductor devices, since software is used to manage production facilities and processing apparatuses such as measuring instruments on a lot basis, production management systems manage production chiefly on a lot basis. In recent years, systems which manage production on a wafer basis have also been considered.
In the input processing method and lot processing method according to the above-described production management system, where production is managed on a lot basis, production processes are previously stored in a host computer or a storage means connected to the host computer. The host computer selects processing conditions according to each lot number and operating conditions from the stored production processes and informs a processing apparatus of the selected processing conditions. When processing for each lot ends, the processing history in the processing apparatus is stored in a storage means via the host computer.
In the production management system described above, the structures of the storage means, control means, and so on constituting the production management system are determined by the unit of objects which are under production control and also by output information. For example, in a production management system where production is controlled on a lot basis, a plurality of wafers in a lot cannot be controlled individually. Similarly, in a production management system designed to control a plurality of wafers individually, individual chips on wafers cannot be managed individually.
For example, in a production management system for managing production on a lot basis, individual wafers in a lot cannot be controlled. That is, their individual processing conditions, processing histories, etc. cannot be managed if the processing conditions for individual wafers differ. For instance, when instructions regarding processing conditions for individual wafers need to be given, the processing conditions for the individual wafers are added, in the form of messages, to information which is used to manage the lot. When the relevant process is performed, the wafers are processed according to the messages. Since the messages are not created by the production management system, what is controlled by the production management system cannot be extended to the processing histories of each of the wafers.
Due to increases in the diameters of processed wafers and the subsequent reduction in the amount processed per batch by processing apparatuses, (for example, reductions which shift processing from batch processing to individual sheet processing, or from individual sheet processing to processing of portions of wafers), and further, due to production of small numbers of various kinds of components (e.g. production of ASICs [application specific integrated circuits]), production management for individual chips mounted on each wafer is required.